Dynamic relaxation studies performed on 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) based hyperbranched polymers (HBPs) have not yet been extended to their dendrimer analogues which require considerable synthetic efforts. The aim of the study is to compare dielectric behaviors of a bis-MPA based second-generation HBP, Boltorn H20, with its dendrimer analogue and study their correlation with hydrogen bonding organization which is affected by structure dispersity and irregularity. In this study, a monodispersed, ideally structured second-generation dendrimer G2 was prepared via anhydride coupling method. FITR and NMR analysis were performed to study hydrogen bonding organization in H20 and G2. Stronger hydrogen bonding association was found in G2. Dielectric spectroscopy was employed to study the diploe relaxation and electrical conductivity behavior of both two polyesters. The γ-relaxation of both H20 and G2, which is originated from rotation of terminal hydroxyl groups, followed Arrhenius dependence. The effect of stronger hydrogen bonds on hydroxyl motion was reflected by the higher activation energy of G2. The conductivity relaxation, contributed by proton hopping along hydrogen bonds, showed non-Arrhenius dependence above Tg and Arrhenius dependence below Tg. This indicates that the translational motions of chargers become increasingly faster than structural motion and eventually decouple from it as temperature is approaching to Tg. Larger decoupling of G2 suggests higher mobility of protons in the system which can be facilitated by stronger hydrogen bonding.

Comparative study of dielectric relaxation and electrical conductivity behavior correlated to hydrogen bonding organization between Bis-MPA based hyperbranched polymer and dendrimer

255th National Meeting (2018)

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